JAVA中的多线程(六)

生产者消费者

class Resource
{
    private String name;
    private int count = 1;
    private boolean flag = false;
    
    public synchronized void set(String name)
    {
        while(flag)
            try{this.wait();}catch(Exception e){}
        this.name = name+"--"+count++;
        System.out.println(Thread.currentThread().getName()+"...生产者..."+this.name);
        flag = true;
        this.notifyAll();
    }
    
    public synchronized void out()
    {
        while(!flag)
            try{this.wait();}catch(Exception e){}
        System.out.println(Thread.currentThread().getName()+"...消费者..."+this.name);
        flag = false;
        this.notifyAll();
    }
}

class Producer implements Runnable
{
    private Resource res;
    
    Producer(Resource res)
    {
        this.res = res;
    }
    
    public void run()
    {
        while(true)
        {
            res.set("+TT+");
        }
    }
}

class Customer implements Runnable
{
    private Resource res;
    
    Customer(Resource res)
    {
        this.res = res;
    }
    
    public void run()
    {
        while(true)
        {
            res.out();
        }
    }
}
class ProducerCustomerDemo
{
    public static void main(String[] args)
    {
        Resource r = new Resource();
        
        Producer pro = new Producer(r);
        Customer con = new Customer(r);
        
        Thread t1 = new Thread(pro);
        Thread t2 = new Thread(con);
        
        t1.start();
        t2.start();
    }
}

 JDK 1.5及以上版本提供了多线程升级解决方法

将同步synchronized替换成显示的Lock操作

将Object中的wait，notify，notifyAll替换成了Condition对象

该对象可以对Lock锁进行获取

import java.util.concurrent.locks.*;
class Resource
{
    private String name;
    private int count = 1;
    private boolean flag = false;
    
    private Lock lock = new ReentrantLock();
        
    private Condition condition_pro = lock.newCondition();
    private Condition condition_con = lock.newCondition();
    
    public void set(String name)throws InterruptedException
    {
        lock.lock();
        try
        {
            while(flag)
                condition_pro.await();
            this.name = name+"--"+count++;
            System.out.println(Thread.currentThread().getName()+"...生产者..."+this.name);
            flag = true;
            condition_con.signal();
        }
        finally
        {
            lock.unlock();
        }
    }
    
    public void out() throws InterruptedException
    {
        lock.lock();
        try
        {
            while(!flag)
                condition_con.await();
            System.out.println(Thread.currentThread().getName()+"...消费者..."+this.name);
            flag = false;
            condition_pro.signal();
        }
        finally
        {
            lock.unlock();
        }
    }
}

class Producer implements Runnable
{
    private Resource res;
    
    Producer(Resource res)
    {
        this.res = res;
    }
    
    public void run()
    {
        while(true)
        {
            try
            {
                res.set("+TT+");
            }
            catch(InterruptedException e)
            {
                
            }
        }
    }
}

class Customer implements Runnable
{
    private Resource res;
    
    Customer(Resource res)
    {
        this.res = res;
    }
    
    public void run()
    {
        while(true)
        {
            try
            {
                res.out();
            }
            catch(InterruptedException e)
            {
                
            }
        }
    }
}
class ProducerCustomerDemo
{
    public static void main(String[] args)
    {
        Resource r = new Resource();
        
        Producer pro = new Producer(r);
        Customer con = new Customer(r);
        
        Thread t1 = new Thread(pro);
        Thread t2 = new Thread(con);
        Thread t3 = new Thread(pro);
        Thread t4 = new Thread(con);
        
        t1.start();
        t2.start();
        t3.start();
        t4.start();
    }
}